UPDATE: Or not, as this dialog's been around for a while as per 9to5Mac's @llsethj.
Developer Frasier Spears posted the above "curious" iTunes dialog to Twitter. It appeared when he hit "Update All". We have no way of knowing exactly it means, but we're hoping it means upgrade pricing is finally coming to the app store.
As background, one of the problems still facing developers has been the inability to offer paid upgrades. Either they had to give away new versions for free, or they had to create new apps with no way to discount the price to existing users.